Embodiments of the present specification relate to imaging, and more particularly to automated measurement of fetal head descent in a birth canal during labor.
Ultrasound imaging has been employed for a wide variety of applications. During the process of ultrasound scanning, a clinician attempts to capture a view of a certain anatomy which confirms/negates a particular medical condition. Once the clinician is satisfied with the quality of a view or a scan plane, the image is frozen to proceed to a measurement phase. For example, ultrasound images are routinely used to assess gestational age (GA) and weight of a fetus or to monitor cardiac health of a patient. Subsequent to the selection of a desired image, ultrasound measurements of specific features of fetal anatomy such as the head, abdomen or the femur from two-dimensional (2D) or three-dimensional (3D) image data may be obtained. These measurements are used in the determination of GA, assessment of growth patterns, and identification of anomalies. Similarly, for cardiac applications, thicknesses of cardiac walls are routinely measured by cardiologists to check for cardiomyopathy.
In recent times, ultrasound scanning has also been used in labor and delivery applications. The current practice in labor and delivery is based on a digital examination to estimate the fetal head position. Digital examination of fetal descent using transvaginal imaging remains the “gold standard” for evaluating a fetal head station. Unfortunately, the digital examination is subjective and inaccurate with high inter-observer variability.
Recent studies have recommended use of transperineal ultrasound to allow for objective quantification of fetal head descent in the birth canal. In addition, use of multiple measurements in conjunction with transperineal ultrasound has been suggested for the quantification of the fetal head descent. There is growing evidence suggesting that an angle of progression may provide an objective, more reproducible and accurate tool to monitor progression of the fetal head in the birth canal during labor. However, manually measuring the angle of progression using the ultrasound images is a user-dependent and time-consuming method. Moreover, there is substantial variability in the measurement of angle of progression and interpretation of fetal station even among experienced clinicians. Consequently, this variability in the measurement of the angle of progression adversely affects clinical evaluation of the progress of labor. Additionally, two-dimensional transperineal ultrasound images having artifacts such as caput and/or molding further exacerbate the evaluation of the fetal head descent.
It is therefore desirable to enhance accuracy of measurement of the angle of progression that is independent of the experience of the user. In particular, it is desirable to automate the measurement of the angle of progression to enhance the skill and utilization of clinicians or paramedics across the world and also encourage adoption of ultrasound to assist labor in geographies with fewer experienced sonographers. The automated measurement of the angle of progression aids in reducing the variability in assisting patients during labor. Moreover, the automated measurement of the angle of progression will provide a consistent and objective measure that is independent of the experience of staff and/or doctors in the labor room.
Currently available techniques entail combining position tracking technology with advanced ultrasound imaging to objectively determine the fetal head station in the labor room. However, these techniques disadvantageously call for manual marking of points on the pelvis or entail use of a position sensor followed by marking known fetal head landmarks on the ultrasound image to determine the spatial position of the fetal head in relation to the pelvic bone. However, the need for manual intervention while using these techniques impedes the automation of the process of monitoring the fetal head descent during labor.